Ground squirrel: Invasive species or native to island?

Ground squirrel parka made by Susan Malutin and Grace Harrod, 1999. (Photo courtesy the Alutiiq Museum)

An archaeologist is studying the ancient ground squirrel on Chirikof Island and trying to figure out when the squirrel would have been introduced to the area and how.

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Catherine West is a research assistant professor at Boston University and has been coming to do archaeology in the Kodiak area since the early 2000’s. She said this project is the first one she’s directed, and she received a grant from National Geographic to study the historic presence of the animal on Chirikof.

West said she and a couple of colleagues dug up animal bones at different sites on Chirikof, and they found a lot of squirrel bones there.

“So far as we knew, squirrel had been introduced in the historic period sometime in the late 1800s, early 1900s by fox farmers, but because we were finding them in sites that were much, much older, we thought that this would be an interesting twist in understanding the history of this island to learn more about this animal whose history is really poorly understood,” West said.

West said she and her colleagues radiocarbon dated the bones and discovered the squirrels have been on the island for at least a couple thousand years.

“We know that people were harvesting them for at least 2,000 years because we found cut marks on those bones,” West said. “A lot of the bones were burned, probably in a fire and thrown into a trash dump, so it’s obvious that people were using them, and we think probably they were certainly being used to make parkas, and maybe people were eating the meat also from the squirrels.”

West said they’ve discovered DNA evidence that the ancient squirrels are related to the ones currently inhabiting the island, but at the same time some resource managers identify the squirrels as destructive to other animals in the Gulf of Alaska. That begs the question of which animals count as native and which are invasive?

“If they’re historically introduced they might be subject to eradication to preserve birds primarily on these island, but what does it mean when squirrels have been there for 2,000 years and still might be destructive in some way?” West said. “Were they introduced by people, did they get there by rafting, have they been there longer than that? Their history becomes much more complex and so defining them as an invasive species becomes much more difficult in our opinion.”

West found a number of other animals in the collection of bones from the island, from dolphins to small birds, but said the massive number of squirrel bones points to a possible hunting site specific to squirrel.